Optical disk device

ABSTRACT

An optical disk provided with a land region and a groove region that are formed on a substrate, the land region and groove region being used as a recording track that is the medium of the recording/playback of information signal, and a pre-pit region that is formed at the boundary part of neighboring land region and groove region and is disposed every other boundary part, the pre-pit region including specific information. Characteristically, the specific information&#39;s in neighboring pre-pit regions are not aligned in the radius direction of the optical disk.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application is a division of Application Ser. No.09/398,204, filed Sep. 17, 1999, now pending, and related to aconcurrently filed application, entitled: Optical Disk Device (AttorneyDocket No. 017661-0185), and based on Japanese Patent Application No.10-262794, filed Sep. 17, 1998, by Toshiaki Iwanaga. This applicationclaims only subject matter disclosed in the parent application andtherefore presents no new matter.

[0002] 1. Field of the Invention

[0003] This invention relates to a disk format on optical disk, and toan optical disk device that can conduct the recording and playback ofsuch an optical disk.

[0004] 2. Background of the Invention

[0005] In recent years, for a rewritable optical disk with a largecapacity, a land/groove recording system that a region between groovesis also used as an information track, as well as a groove provided as aguide trench on optical disk is suggested. The land and groove may becalled convex part and concave part, respectively, or calledinter-groove part and groove part, respectively. First, an optical diskused in the conventional land/groove recording system is explained.

[0006]FIG. 1 is a partial enlarged plan view showing a conventionaloptical disk that is described in Japanese patent No. 2,663,817. In FIG.1, G indicates a groove region, L indicates a land region, Tp indicatesa track pitch, P indicates a pre-pit, and BS indicates a focused beamspot. Also, “identification signal region” in Japanese patent No.2,663,817 is called “header region” herein. In this disk format, aheader region including address information is shared between adjacentgroove G and land L, and at least a part of information signal includedin header region is shifted by Tp/4 to the center line of groove G andto the center line of land L, and in at least part of optical disk, theheader region and recording data region each are formed in a radialpattern.

[0007]FIG. 2 is a block diagram showing the composition of an opticaldisk device used for the optical disk above. In FIG. 2, 100 is theoptical disk, 103 is a half mirror serving as a beam splitter, 104 is anobjective lens to converge collimated light passed through the halfmirror 103 onto the optical disk 100, 105 is a collimator lens tocollimate light from a semiconductor laser 106, and 108 is an opticaldetector to receive reflected light from the optical disk 100 passingthough the objective lens 104 and the half mirror 103. The opticaldetector is composed of two light-receiving parts that are divided inparallel to the track direction (tangential direction of circumference)of the optical disk to obtain the tracking error signal. 102 is anactuator supporting the objective lens 104. Meanwhile, part 101 enclosedby a dotted line in FIG. 2 is attached to a head base (not shown), andcompose an optical head.

[0008] On the other hand, 110 is a differential amplifier to whichdetection signal to be output from the optical detector 108 is input.117 is a polarity inverter to which tracking error signal from thedifferential amplifier 110 and control signal L4 from a systemcontroller 118 described later are input, and which controls thepolarity of tracking error signal output to a tracking controller 116according to the control signal L4. Hereupon, regarding the polarity oftracking control, when tracking error signal is input, with its polarityunaltered, from the differential amplifier 110 to the trackingcontroller 116, the tracking is pulled into the recording track ofgroove G. 116 is the tracking controller to which output signal from thepolarity inverter 117 and control signal L1 from the system controller118 are input, and which outputs tracking control signal to a driver 122and a traverse controller 121. 109 is an adder amplifier to whichdetection signal output from the optical detector 108 is input and whichoutputs add signal. 112 is a waveform shaper to which a RF componentfrom the adder amplifier is input, and which outputs digital signal to aplayback signal processor 113 and a address playback circuit 114. 113 isthe playback signal processor which outputs playback data to the outputterminal. 114 is the address playback circuit to which digital signalfrom the waveform shaper 112 is input, and which outputs address signal.115 is an address calculator to which address signal from the addressplayback circuit 114 and control signal L4 from the system controller118 are input, and which outputs address signal to the system controller118.

[0009] Also, 121 is the traverse controller which outputs drive currentaccording to control signal from the system controller 118. 107 is atraverse motor which moves the optical head 101 in the radius directionof the optical disk 100 according to drive current from the traversecontroller 121. 119 is a record signal processor to which record data isinput and which outputs record signal to a laser (LD) driver 120. 120 isthe LD driver to which control signal from the system controller 118 andrecord signal from the record signal processor 119 are input, and whichsupplies drive current to the semiconductor laser 106. 122 is the driverto which tracking control signal from the tracking controller 116 isinput and which supplies drive current to the actuator 102. Meanwhile,the system controller 118 which outputs control signal L1, L4 to thetracking controller 116, the traverse controller 121, the addresscalculator 115, the polarity inverter 117, the record signal processor119 and the LD driver 120, and to which address signal from the addresscalculator 115 is input.

[0010] The operation of the conventional optical disk device thuscomposed is explained below.

[0011] Light output from the semiconductor laser 106 is collimated bythe collimator lens 105, passed through the beam splitter 103, convergedonto the optical disk 100 by the objective lens 104. Laser lightreflected on the optical disk 100 holds the information of record track,passing through the objective lens 104, being led through the beamsplitter 103 to the optical detector 108. The optical detector 108converts a variation in light quantity distribution of light beamsupplied into electrical signal, outputting it to the differentialamplifier 110, the adder amplifier 109. The differential amplifier 110current-voltage-converts (I-V conversion) currents input, taking thedifference of both voltages, outputting it as push-pull signal. Thepolarity inverter 117 judges whether the track accessed is a land or agroove according to control signal L4 from the system controller 118,inverting the polarity, for example, only when the track is a land. Thetracking controller 116 outputs tracking control signal to the driver122 according to the level of tracking error signal input, the driver122 supplies current to the actuator according to this signal to controlthe position of the objective lens 104 in the radius direction acrossthe recording track. Thereby, the optical spot can scan precisely on thetrack.

[0012] On the other hand, the adder amplifier 109current-voltage-converts (I-V conversion) two currents output from thelight-receiving part 108, adding both, outputting it as add signal tothe waveform shaper 112. The waveform shaper 112 shapes data signal andaddress signal with an analogue waveform into a pulse waveform bydata-slicing by a certain threshold value, outputting it to the playbacksignal processor 113 and the address playback circuit 114. The playbacksignal processor 113 demodulates digital data signal input, conductingthe processing of error correction etc. to output it as playback data.The address playback circuit 114 demodulates digital address signalinput, outputting it as position information on the disk to the addresscalculator 115. The address calculator 115 calculates the address of asector accessed from address signal read out from the optical disk 100and land/groove signal from the system controller 118. The calculationmethod is to judge referring to an address map etc. and then output thejudgement signal.

[0013] The system controller 118 judges whether the light beam currentlylocates at a desired address based on this address signal. The traversecontroller 121 outputs drive current to the traverse motor 107 accordingto control signal from the system controller 118 when shifting theoptical head 101, thereby the optical head 101 is shifted to a targettrack. Hereupon, the tracking controller 116 suspends the tracking servoaccording to control signal L1 from the system controller 118. Also, inthe normal playback mode, the traverse motor 107 is driven according totracking error signal input from the tracking controller 116, and theoptical head 101 is moved gradually in the radius direction as theplayback operation proceeds. The record signal processor 119 adds anerror correction code etc. to record data input, outputting it asencoded record data to the LD driver 120. When the system controller 118sets the recording mode by control signal, the LD driver 120 modulatesdrive current applied to the semiconductor laser 106 according to recordsignal. Thereby, the intensity of light spots projected onto the opticaldisk 100 varies according to the record signal, record pits are formed.On the other hand, in the playback operation, the LD driver 120 is setto the playback mode by control signal, the drive current is controlledso that the semiconductor laser 106 emits light at a constant intensity.Thereby, the detection of record pit and pre-pit on record track isenabled.

[0014] Meanwhile, Japanese patent No. 2,663,817 discloses not only atechnique that the detection of record pit and pre-pit is conductedusing track add signal but also a way to detect a pre-pit usingpush-pull signal which is track difference signal. Namely, since theheader region is positioned offsetting by Tp/4 from the record track inthe radius direction, the detection using push-pull signal is enabled.

[0015] However, the optical disk and optical disk device using the landregion and groove region as an information track have a significantweakness for the defocusing of focused beam. Namely, due to an error inthe manufacturing of head or a deterioration in head performance withage, so-called defocusing that focused beam is converged deviating froma right focus position occurs. Hereupon, in the optical disk describedabove, information of adjacent header regions affects as a crosstalk.Especially, when one address information is a signal of short mark andother to crosstalk is a signal of long mark, a significant distortion ofwaveform is observed and an error in the reading of address informationoccurs. In this case, since the header region needs to be played backwhile waiting for the rotation, the throughput may be reduced. Also,when it is played back again, the reading error is highly like to recur.Therefore, since it may be registered as a defect sector, thereliability of device and disk must be thus reduced.

[0016] Also, in the optical disk device above, since the header regionincluding address information is shared between adjacent groove andland, when an address to start the recording/playback is designated, thesystem controller judges whether the designated address is the landregion or groove region by referring to an address map etc. Then,judgement signal (polarity signal) is output to the tracking servosystem. After the tracking, detection signal of the physical address isaddress converted by the judgement signal, thereby it is judged whetherthe tracking is carried out to the designated address. However, forexample, when a large track offset occurs due to the failure oftracking, the tracking to the land or groove may not be performed asdesignated by polarity signal. Therefore, the judgement of addressbecomes unsuccessful and the operation of device goes out of control.

[0017] Also, in the header region, the influence of the pre-pit to servoerror signal is to cause the focus offset and the disorder of trackerror signal, thereby incurring a unstable recording/playback. At thesame time, when starting the recording after passing the header region,depending on the composition of optical head, there occurs a focusoffset due to the chromatic aberration of objective lens, by aphenomenon called a jump of wavelength in semiconductor laser. Thisfocus offset interferes with the focus offset occurring near the headerregion, thereby the focus control is made to be further unstable,causing a failure in recording.

SUMMARY OF THE INVENTION

[0018] Accordingly, it is an object of the invention to provide anoptical disk with an enhanced reliability.

[0019] It is a further object of the invention to provide an opticaldisk device with an excellent stability of recording/playback.

[0020] According to the invention, an optical disk, comprises:

[0021] a land region and a groove region that are formed on a substrate,the land region and groove region being used as a recording track thatis the medium of the recording/playback of information signal; and

[0022] a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including specific information;

[0023] wherein the specific information's in neighboring pre-pit regionsare not aligned in the radius direction of the optical disk.

[0024] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0025] means for outputting, in advance, as identifier 1 whether arecording track scanned by light beam is a land region or a grooveregion;

[0026] a track region detection means for detecting whether therecording track scanned by light beam is a land region or a grooveregion and outputting the detection result as identifier 2;

[0027] an address information extraction means for extracting addressinformation from the pre-pit region scanned by light beam; and

[0028] means for conducting the address calculation by receiving theinputs of the identifier 1, identifier 2 and address information.

[0029] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0030] a track region detection means for detecting whether a recordingtrack scanned by light beam is a land region or a groove region;

[0031] means for detecting a push-pull signal as a track differencesignal based on the output of the track region detection means;

[0032] a calculation means for calculating the track difference signalby setting a subtraction ratio between one signal output and othersignal output of the two signal outputs used to calculate the trackdifference signal; and

[0033] means for detecting address information from the output of thecalculation means.

[0034] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0035] a header region detection means for outputting header regionsignal to indicate the position of a header region including the pre-pitregion from a track add signal;

[0036] means for outputting first-order differential signal from apush-pull signal as a track difference signal;

[0037] means for outputting differential cross signal from the zerocross signal of the first-order differential signal;

[0038] a window comparator means for binarizing the amplitude of thefirst-order differential signal at a predetermined slice level; and

[0039] a logical operation means for outputting track region detectionsignal to determine whether a track scanned by light beam is a landregion or a groove region, from the header region signal, differentialcross signal and output signal of the window comparator means.

[0040] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0041] means for outputting signal to detect whether a recording trackscanned by light beam is a land region or a groove region;

[0042] a header region detection means for detecting a header regionincluding the pre-pit region; and

[0043] a servo error detection means for sampling a track error signalvalue at an arbitrary time before the output time of the header regiondetection means, and holding the track error signal value an arbitrarytime or conducting an operation of the track error signal value andarbitrary waveform signal then outputting the operation result as servoerror signal.

[0044] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0045] means for outputting signal to detect whether a recording trackscanned by light beam is a land region or a groove region;

[0046] a header region detection means for detecting a header regionincluding the pre-pit region; and

[0047] a servo error detection means for sampling a focus error signalvalue at an arbitrary time before the output time of the header regiondetection means, and holding the track error signal value an arbitrarytime or conducting an operation of the focus error signal value andarbitrary waveform signal then outputting the operation result as servoerror signal.

[0048] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0049] means for outputting envelope signal or peak hold signal fromtrack add signal to be input;

[0050] means for binarizing the envelope signal or peak hold signal tobe input;

[0051] a burst detection means for detecting burst signal with aspecific mark included in the pre-pit region then outputting burstdetection signal; and

[0052] a logical operation means for outputting binarized signal nearlyenclosing the pre-pit region based on the output signal of thebinarizing means and the burst detection signal.

[0053] According to another aspect of the invention, an optical diskdevice for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, the land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region that is formed at the boundary part ofneighboring land region and groove region and is disposed every otherboundary part, the pre-pit region including address information,comprises:

[0054] means for generating replica signal under a condition that acrosstalk component from the neighboring pre-pit region at a positionwhere address information is played back is clearly detected; and

[0055] a crosstalk removing means for removing the replica signal ascrosstalk component from a signal component played back.

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The invention will be explained in more detail in conjunctionwith the appended drawings, wherein:

[0057]FIG. 1 is an enlarged partial plan view showing the format of theconventional optical disk,

[0058]FIG. 2 is a block diagram showing the composition of theconventional optical disk device,

[0059]FIG. 3 is an enlarged partial plan view showing the format of anoptical disk in a first preferred embodiment according to the invention,

[0060]FIG. 4 is an illustration showing an example of the sector formatof optical disk according to the invention,

[0061]FIG. 5 is an enlarged partial plan view showing the format of anoptical disk in a second preferred embodiment according to theinvention,

[0062]FIG. 6 is a block diagram showing main part of an optical diskdevice in a first preferred embodiment according to the invention,

[0063]FIG. 7 is an illustration showing the idea of track error offsetsignal generated at the header region,

[0064]FIG. 8 is a block diagram showing main part of an optical diskdevice in a second preferred embodiment according to the invention,

[0065]FIG. 9 is a block diagram showing main part of an optical diskdevice in a third preferred embodiment according to the invention,

[0066]FIG. 10 is a waveform diagram showing the operation of the opticaldisk device in FIG. 9,

[0067]FIG. 11 is block diagram showing main part of an optical diskdevice in a fourth preferred embodiment according to the invention,

[0068]FIG. 12 is block diagram showing main part of an optical diskdevice in a fifth preferred embodiment according to the invention,

[0069]FIG. 13 is an illustration showing the idea of focus error offsetsignal generated at the header region,

[0070]FIG. 14 is block diagram showing main part of an optical diskdevice in a sixth preferred embodiment according to the invention,

[0071]FIG. 15 is a waveform diagram showing the operation of the opticaldisk device in FIG. 14, and

[0072]FIG. 16 is block diagram showing main part of an optical diskdevice in a seventh preferred embodiment according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] The preferred embodiments of the invention will be explainedbelow, referring to the drawings.

[0074] Here, (1,7)RLL is used as a modulation system and mark edgerecording are used as a recording system. As the control system for therotation of optical disk, ZCLV (zoned constant linear velocity) is used.In this embodiment, taken as an example of optical disk allowing therecording/playback is a phase change (PC) type optical disk that therecording is conducted according to the change of real reflectivity.Also, for example, a focused beam diameter (1/e²) is 0.95 μm, and eachtrack width of land/groove is 0.58 μm.

[0075] First, an optical disk according to the invention is explainedbelow.

[0076]FIG. 3 is an enlarged plan view showing the recording surface ofan optical disk in the first preferred embodiment according to theinvention. As shown, a header region is placed between recording regionsin the scanning direction of a light beam to scan each land region(Land) as a convex part of an optical disk and each groove region(Groove) as a concave part adjacent to the land region, i.e., in thecircumferential direction of the optical disk. In the header region andon the boundary part between each of the land regions (Lands) and thegroove regions (Grooves), pre-pit regions that show physical addressinformation common to a land region (Land) and a groove region (Groove)are disposed at every other boundary part. Namely, the pre-pit regionsare disposed deviating by Tp/4 at every-other boundary part with respectto a track pitch Tp of the land region or groove region. Thisarrangement is similar to that in the conventional optical disk. Toensure that a pre-pit region in a header region neighboring in theradial direction of the optical disk is not aligned, in the radialdirection, with a pre-pit region on a neighboring boundary part, one ofthe neighboring pre-pit regions is alternately shifted by several bytes,for example, backward or forward in the circumferential direction of theoptical disk. Also, it is, of course, applicable to shift the pre-pitregion alternately forward and backward in each sector in thecircumferential direction so that adjacent pre-pit regions are notaligned in the radial direction.

[0077] Here, an amount SH of the shifting described above in the pre-pitregion is explained below.

[0078]FIG. 4 shows a format composition of the pre-pit. In FIG. 4, ofthe several pre-pits shown in FIG. 3, two pre-pit regions 10, 11neighboring in the radial direction are shown. Each of these pre-pitregions 10, 11 includes a composition with doubled sector addressinformation regions. In each pre-pit region 10, 11, to perform thedoubled sector address information regions, there are provided two setsof address marks AM (2B: 2byte), sector addresses ID1, ID2 (3B), anderror correction codes IED1 (2B) of ID1, ID2. Also, there are providedVFO1 (variable frequency oscillator) (26B) before the sector addressinformation region, and VFO2 (12B) between the sector addressinformation regions. These regions, VFO1 and VFO2, are for the pull-inof clock, and use single-cycle signals, such as a 3T mark. Meanwhile, atthe end of the pre-pit region, post-amble region PA (1B) is provided asa modulation encoding.

[0079] In this case, the shift amount SH is set so that the two sectoraddress information regions in one of the adjacent pre-pit regions, e.g.the pre-pit region 11, are aligned to the regions, VFO1 and VFO2, of theother pre-pit region 10. Also, by the shift amount SH, the sectoraddress information regions in the other pre-pit region are aligned tothe regions, VF01 and VF02, of the one pre-pit region in the radiusdirection. Meanwhile, given blank regions, TA1 and TA2 which are formedas mirror regions, are provided at both sides of each pre-pit region inthe circumference direction and between the pre-pit region and therecording region in the header region. These are also needed to give atransfer time to a cutting device to make a pre-format when moving lightbeam by Tp/4 in the radius direction in case of one-beam cutting device.However, the main object is to facilitate the detection of header regionby forming TA1 and TA2 as mirror regions.

[0080] In conducting the recording/playback of information by scanninglaser light onto the optical disk, defocusing or radial tilting,described earlier in prior art, to one pre-pit region as a scan targetmay occur. However, the adjacent pre-pit region, as a crosstalkcomponent, to the sector address information is VFO1 and VFO2 regions,where 3T marks, which are of short-mark signal, are carved and the markwidth is physically smaller than sector address ID1 or ID2, unlessmaking a special artifice by the cutting device. Therefore, even fordefocusing of about ±1 μm, the crosstalk is less than −26 dB, which is atolerance of optical disk device. Also, since the VFO1 and VFO2 regionsare of single-cycle mark and the identification of crosstalk componentis therefore clear, a method of removing the crosstalk described lateris also applicable. Thus, by shifting by the shift amount SH theneighboring pre-pit region in the header region, the harmful effect ofcrosstalk can be reduced significantly without reducing the formatefficiency.

[0081] Even when the composition of the pre-pit region described aboveis employed, for a narrower track pitch Tp to provide a higher-densitymedium, the VFOs in the neighboring pre-pit regions may interfere witheach other, affecting the identification of data when the crosstalkoccurs due to defocusing. In this case, as shown in FIG. 4, at least themutual recording mark edges 12 of the VFO1 regions in the neighboringpre-pit regions only have to be formed aligned in the radius direction.Thus, by aligning the recording mark edges in the radius direction, theinterference between the VFOs in the neighboring pre-pit regions can besuppressed.

[0082] Meanwhile, as to the VFO2 region, depending on the length of AM,ID1 and IED1, the recording mark edges may not be aligned in the radiusdirection. However, in the VFO2 region, when conducting only the pull-inof phase using PLL (phase lock loop) circuit (not shown) for theextraction of playback clock, the problem caused by that the recordingmark edges are not aligned in the radius direction does not occur sincethe phase lock can be obtained by a few clocks. Also, though not shown,in order to align certainly the recording mark edge of VFO2 region inthe radius direction, it is applicable that a mirror region of severalchannel clocks is, for example, inserted between the IED1 and VFO2 inthe adjacent pre-pit region 11 to be shifted. In this case, although thelength of pre-pit region differs between the adjacent pre-pit regions,the VFO regions do not interfere with each other even for a furtherhigh-density medium, and the extraction of clock can be made stable. Inthis embodiment the pre-pit region is of the doubled composition, but itcan be simplified by using a singled composition. Also, a tripled orquadrupled composition is applicable similarly.

[0083]FIG. 5 is an enlarged plan view showing the recording surface ofan optical disk in the second preferred embodiment according to theinvention. The difference from the optical disk in FIG. 3 is that inorder not to align neighboring pre-pit regions in the radius direction,the pre-pit regions are shifted alternately, for example, forward andbackward in the circumference direction of the optical disk, in theradius direction. Of course, there exist some variations other thanthis. For example, for a predetermined number of tracks, the alternateshifting is made forward, and for another predetermined number oftracks, the alternate shifting is made backward. Although in FIG. 5 theshift amount SH is the same value between the forward and backwardsides, it may be different values therebetween. In any case, provided inthis invention is an optical disk that specific information's ofneighboring pre-pit regions are not aligned in the radius direction toso as to reduce the harmful effect of crosstalk.

[0084] Also, the concept of the sector structure including a sectoraddress as fundamentals of disk format is that the sector address numberof each sector, which is common physical address information to landregion 1 and groove region 2, increases sequentially, n, n+1, n+2, n+3,. . . , where n is a positive integer, in the trace direction of focusedbeam. Herein, the trace direction shown is clockwise from the innercircumference side to the outer circumference side, and addressinformation shown is formed in reference to the groove region. Also, Nis the number of sectors in one physical track, and is a fixed number incase of ZCLV. N is an arbitrary offset number given by an addresscalculation circuit described after, which is used, for example, tofacilitate the address management of land region and groove region. Forexample, M is a fixed value on the entire surface of disk.

[0085] Meanwhile, in the above embodiments, the entire pre-pit region isshifted alternately in the radius direction of optical disk. So, thelengths of TA1 and TA2 vary between neighboring pre-pit regions in theradius direction of optical disk. However, as defined in appendedclaims, the essential feature of optical disk according to the inventionis that sector address regions are not aligned in the radius directionof optical disk. Namely, another embodiment can be, for example,composed so that the lengths of TA1 and TA2 are fixed always and onlythe address region is shifted by an amount of SH. In this case, thelength of VFO1 varies between neighboring pre-pits. Also, when theaddress region after VFO2 is shifted forward, a short mark sequence,such as a VFO mark, can be inserted additionally.

[0086] Also, though not shown, the pre-pit in the header region has ashape of concave/convex and a depth or height of λ/10n to λ/4n, where λis a wavelength of light beam and n is mainly a refractive index ofsubstrate. In fact, when making a initial disk, the physical depth isdetermined by a thickness of resist unless making a special artifice.Therefore, if the depth or height of groove is made λ/8n, the depth orheight of pre-pit becomes equal. Hereupon, though the amplitude of trackerror signal by push-pull system becomes maximum, the modulation degreeof pre-pit reduces to less than the maximum bit depth, λ/4n. Of course,it is well known that this depends on the detection system of trackerror signal. In an error detection system such as heterodyne, theamplitude of track error signal becomes maximum at λ/4n. Therefore, whenusing the push-pull system, the pit depth is set to be, e.g. λ/6n as acompromise point. Of course, when using a phase change type optical diskmedium, the groove depth is also a compromise point considering acrosstalk in the recording region, but it is proved that a good playbackperformance is obtained even when setting about 70 nm nearlycorresponding to a groove depth of λ/6n.

[0087] Further, as to the shape of pre-pit in the header region, thepre-pit needs to have a width equal to or less than the track width ofland/groove. For example, for a focused beam of 0.95 μm and a trackwidth of about 1.58 μm, even under the condition that an external factorsuch as defocusing and radial tilting does not exist, the amount ofcrosstalk from the adjacent header region is such a degree that slightlyexceeds a tolerance of device, −26 dB. Therefore, considering theviewpoint of crosstalk, the width of pre-pit is to be determined takingthe SN ratio of address information identification into account whilekeeping less than the track width.

[0088] Also, in dividing the surface of optical disk into multiplezones, when the zone with is made uniform, the length of the shortestrecording mark within the zone is shorter at the inner circumferenceside and longer at the outer circumference side. Thus, the length of theshortest recording mark on the surface of optical disk must be dispersedamong the zones. If the length of the shortest recording mark is short,a playback error is likely to occur and there may occur a difference inplayback performance of address information in the header region amongthe zones. It is undesirable in the sight of reliability of disk. Toavoid this as far as possible, the number of tracks provided for thezones at the inner and outer circumference sides are reduced so that thelength of the shortest recording mark is almost uniform among the zones.According to this, there is an effect that dispersion in playbackperformance or recording performance among the zones becomes difficultto incur.

[0089] Next, an optical disk device according to the invention isexplained. Meanwhile, in the embodiments below, the composition of theconventional optical disk device shown in FIG. 2 is incorporated intothe background of this invention, and components different from theconventional disk device are shown and explained mainly.

[0090]FIG. 6 is a block diagram showing the main part of an optical diskdevice in the first preferred embodiment according to the invention.

[0091] The optical disk device for conducting the recording/playback ofan optical disk that includes a header region having a pre-pit regionthat is formed on the boundary part of neighboring land region andgroove region and includes address information, the header region beingdisposed every other boundary part, as shown in FIGS. 3 and 5,comprising: a system controller 20 as means for outputting, in advance,identifier 1 to inform whether a recording track to be scanned by lightbeam is a land region or a groove region; a waveform shaper 21 and anaddress playback circuit 24 as a physical address information extractionmeans for extracting physical address information of a header region tobe scanned by light beam; a track region detector 23 as means foroutputting identifier 2 to inform the detection result as to whether arecording track to be scanned by light beam is a land region or a grooveregion; and an address calculator 25 as means for calculating addressfrom identifier 1, identifier 2 and output of the physical addressinformation extraction means, wherein header information is shared byneighboring groove and land.

[0092] Namely, since the conventional optical disk device described inJapanese patent No. 2,663,817 conducts the address calculation usingonly identifier 1 (=L4 in '817) in this embodiment, a misidentificationof address may occur due to the malfunction of optical disk device. So,this invention solves this problem by adding identifier 2 as output ofthe track region detector 23.

[0093] When scanning a land region (Land) or a groove region (Groove) asshown in FIG. 7, low-frequency component signal of header regionsuperposed on track error signal gives a waveform that deviates, like201 or 202, in the positive or negative side from the center 203 oftrack error signal. So, the track region detector 23 detects suchpositive or negative signal, binarizing this, thereby allowing the trackdetection which to detect a land region or a groove region to beobtained as binarized signal “1” or “0”. The logical operation betweenthis binarized signal used as identifier 2 and identifier 1 generatedfrom the system controller 23 is conducted by the address calculator 25composed of, e.g. an EXOR logical circuit. This allows the coincidencedetection between a land or groove region designated and a land orgroove region detected. Therefore, the misidentification of addresscaused by the malfunction of optical disk device can be preventedeffectively.

[0094] Meanwhile, with played-back address information from the addressplayback circuit 24, the read-out address information may be usedunalteredly for groove region, or the linear conversion of address maybe conducted based on a conversion table for land region.

[0095] Also, when not coinciding in the coincidence detection, there-reading of a target address can be conducted by a device operationincluding a retrying.

[0096] Also, even when a malfunction of device such as tracking erroroccur, the device can be prevented from incurring a runaway such as amisidentification of address. Thus, neighboring groove and land canshare header information at a good reliability.

[0097]FIG. 8 is a block diagram showing the main part of an optical diskdevice in the second preferred embodiment according to the invention.

[0098] Like the composition in FIG. 6 (first embodiment), also used isthe track region detector 23 for judging whether a recording track to bescanned by light beam is a land region or a groove region, for anoptical disk that includes a header region having a pre-pit region thatis formed on the boundary part of neighboring land region and grooveregion and includes address information, the header region beingdisposed every other boundary part, as shown in FIGS. 3 and 5.

[0099] In this embodiment, amplifiers A, B and a track error detectioncircuit 111 are additionally provided as means for calculating addressinformation by outputting push-pull signal by changing the output ratioof one signal and other signal from the division type optical detector108, which detects push-pull signal, based on the output of track regiondetector 23.

[0100] The conventional optical disk device described in Japanese patentNo. 2,663,817 conducts the playback of address information usingwide-band push-pull signal. However, in case of the optical disk above,since half of light beam is projected on the pre-pit, there is adifference between amounts of signal received by the two opticaldetectors 108 divided to obtain push-pull signal. Therefore, in theconventional optical disk device, for push-pull signal as differencesignal of the optical detectors, its in-phase component noise is notcancelled and its waveform is distorted. Especially when defocusingoccurs, it is significant on the header side where crosstalk occurs.

[0101] In contrast with this, in the second embodiment of the invention,the circuit is composed so that pushpull signal, as difference signal,with the amplitude ratio between one signal output and other signaloutput changed from 1:1 is output. Thereby, stable push-pull signal witha good SN ratio can be obtained.

[0102] Namely, in this optical disk device, signals from the divisiontype optical detector 108 pass through the amplifiers A and B whoseamplification degree can be set by external signal, then outputtingdifference signal of both the signals from the track error detectioncircuit 111. For example, according to the output of the track regiondetector 23, the amplification degree of the amplifier A to theamplifier B is set, e.g., 1.2 times for land region, and theamplification degree of the amplifier B to the amplifier A is set, e.g.,1.2 times for groove region. Therefore, the in-phase component noise ofpush-pull signal becomes equal and the distortion of waveform can beprevented. Of course, when the amplification degree is set to be zero atonly one side, the detection of signal is conducted at only other side.

[0103] After that, the good push-pull signal output is binarized by thewaveform shaper 21, and then address information is demodulated by theaddress playback circuit 24. Although not shown, the address informationis calculated, with identifiers 1 and 2, by the address calculator inthe same composition as shown in FIG. 6.

[0104]FIG. 9 is a block diagram showing the main part of an optical diskdevice in the third preferred embodiment according to the invention.FIG. 10 is a signal waveform diagram showing the operation of theoptical disk device.

[0105] Like the optical disk device described in Japanese patent No.2,663,817, also used is the playback add signal circuit 109 to outputtrack add signal, and the track error detection circuit 110 to outputtrack error signal 601 as wide-band push-pull signal, which is trackdifference signal, in the optical disk device for an optical disk thatincludes a header region having a pre-pit region that is formed on theboundary part of neighboring land region and groove region and includesaddress information, the header region being disposed every otherboundary part, as shown in FIGS. 3 and 5.

[0106] In this embodiment, additionally provided are a header regiondetector 30 to output header region signal 606 for indicating a headerregion position based on the track add signal, a differential circuit 31to output first-order differential signal 602 based on track errorsignal 601, a zero cross circuit 33 to output differential cross signal603 which is zero cross signal of the firstorder differential signal602, a window comparator 32 to binarize the first-order differentialsignal 602 by two predetermined positive and negative slice levels 620,622 to an amplitude center level 621, and a logical operation circuit 34to output track region detection signal 607 to determine whether a trackscanned by light beam is a land region or a groove region, from theheader region signal 606, the differential cross signal 603 and thewindow comparator's output signals 604, 605.

[0107] The logical operation circuit 34, which is composed of, e.g. RSflip-flop circuit, receives differential cross signal 603 as data input,latching this using the rising edges of window comparator's outputsignals 604, 605 as set signal and reset signal, respectively, passingthrough a polarity inversion circuit, outputting the track regiondetection signal (land/groove signal) 607. Herein, the land region isoutput as “1” and the groove region is output as “0”. Thus, of headerregion signals 606 in FIG. 10, the forward header position correspondsto a header region viewed from the land region, and the backward headerposition corresponds to a header region viewed from the groove region.

[0108]FIG. 11 is a block diagram showing the main part of an opticaldisk device in the fourth preferred embodiment according to theinvention.

[0109] This embodiment is applied to an optical disk device for anoptical disk that includes a header region having a pre-pit region thatis formed on the boundary part of neighboring land region and grooveregion and includes address information, the header region beingdisposed every other boundary part, as shown in FIGS. 3 and 5.

[0110] Like the optical disk device in FIG. 9, also provided is theheader region detector 30 to detect the header region. In thisembodiment, additionally provided are a sample hold circuit 36 to samplea track error signal value at an arbitrary time before the output timeof the header region detector 30 and to hold it for an arbitrary time,an arbitrary waveform generating circuit 35 to generate arbitrarywaveform signal, and an adder circuit 39 to add either or both of outputsignal of the sample hold circuit 36 and control signal from the systemcontroller (its signal output is not shown). Further provided is a phasecompensation filter 37 to output desired servo error signal based onservo error signal output from the adder circuit 39, and a drive circuit38 to drive the tracking actuator according to the servo error signalfrom the phase compensation filter 37. Also, as part of control signalfrom the system controller (not shown), write gate signal (WGATE), whichis gate signal for the start of recording, may be used to control theadd timing of arbitrary function. Alternatively, it may be added always.

[0111] As shown in FIG. 7, when light beam scans the header region,though the size and sign vary depending on the land region scanning orgroove region scanning, the track error signal 201 or 202 incurs a largeoffset. This is because the header region is shifted by nearly halfpitch from the land or groove region where light beam scans andtherefore a low-frequency component of the header region superposed ontrack error signal as push-pull signal causes a track offset. Because ofthis, track error signal after passing the header region makes atransient response and, in some cases, continues making the transientresponse. In such a condition that the tracking control is unstable,there may occur a problem that the following header address cannot beplayed back and the sector recording cannot be carried out continuously.

[0112] So, in this embodiment, the unstable-tracking-control conditioncan be avoided by using servo error signal from the sample hold circuit36 that uses the output of header region signal from the header regiondetector 30, holding a track error signal value of at least severalbytes of sector format before the output time, from the finish of headerregion signal until just before the recording starts.

[0113] However, even in this composition, when the transfer functionvaries due to a deterioration of actuator system with age, the trackingcontrol may be unstable. So, in this embodiment, further by measuringsignal of track offset waveform occurring at the header region to bedetected by the header region detector 30 by a previous learning etc.,then, for example, subtracting this from the servo error signal in theadder circuit 39, the track follow-up performance can be stabilized.Also, other than the simple reverse function of track offset waveform,an arbitrary waveform generated by the arbitrary waveform generatingcircuit 35 can be added or subtracted to produce servo error signalwhile securing the stability of the servo control system includingactuator system.

[0114] The arbitrary waveform may be, for example, a rectangular pulsewith arbitrary height and width. Here, the arbitrary values may bedetermined taking a step response waveform of the servo system includingactuator system into account. Also, they may be, of course, a DC valuesimply. This corresponds to the simple adding/subtracting of trackoffset, and, in this case, by using write gate signal (WGATE) which isgate signal for the start of recording, the timing of adding/subtractingmay be controlled. Thus, the track offset can be switched between theplayback and the recording. Also, the selection of signal from thearbitrary waveform generating circuit 35 can be conducted based onland/groove signal from the system controller or the track regiondetector, described earlier, that conducts the detection of land/groovesignal to detect whether the recording track scanned by light beam is aland region or a groove region.

[0115] Meanwhile, though not shown, the arbitrary waveform generatingcircuit 35 is, for example, composed so that an A/D converter takes intrack error signal, e.g., only near the header region for apredetermined time, accumulating it into a RAM memory, and a D/Aconverter converts it when outputting the signal. By this composition,the reverse function of track offset waveform can be obtained. Also,when generating a true arbitrary waveform, by providing an operationmeans to develop the function on a RAM memory, the signal can be outputby using a D/A converter. Also, many kinds of arbitrary waveforms canbe, of course, prepared in advance by the address management on RAM.

[0116]FIG. 12 is a block diagram showing the main part of an opticaldisk device in the fifth preferred embodiment according to theinvention.

[0117] This embodiment is applied to an the optical disk device for anoptical disk that includes a header region having a pre-pit region thatis formed on the boundary part of neighboring land region and grooveregion and includes address information, the header region beingdisposed every other boundary part, as shown in FIGS. 3 and 5.

[0118] In this embodiment, in addition to the division type opticaldetector 108 for the detection of track error signal, a division typeoptical detector 150 for the detection of focus error signal isprovided.

[0119] Like the optical disk device in FIG. 11, provided in thisembodiment are the header region detector 30 to detect the headerregion, a sample hold circuit 41 to sample a focus error signal value atan arbitrary time before the output time of the header region detector30 and to hold it for an arbitrary time, an arbitrary waveformgenerating circuit 40 to generate arbitrary waveform signal, an addercircuit 44 to add either or both of output signal of the sample holdcircuit 41 and control signal from the system controller (its signaloutput is not shown), a phase compensation filter 42 to output desiredservo error signal, and a drive circuit 43 to drive the focus actuator.Also, as part of control signal from the system controller (not shown),write gate signal (WGATE), which is gate signal for the start ofrecording, may be used to control the add timing of arbitrary function.Alternatively, it may be added always.

[0120] As shown in FIG. 13, when light beam scans the header region, notonly track error signal but also focus error signal 204 incurs a largeoffset. It is assumed that this is affected by the optical turning oftrack error signal into focus error signal or a phase difference.Hereupon, it is apparent that excessive drive current is supplied to theactuator, thereby the focus control becomes unstable. However, theactuator itself cannot move even when an optical offset occurs at theheader region. Because, to the servo control band, in general, thelength of header region is not made to be long, therefore the playbackof header region incurs no problem.

[0121] However, as shown in FIG. 13, when starting the recording afterpassing the header region, depending on the composition of optical head,there occurs a focus offset due to the chromatic aberration of objectivelens, by a phenomenon called a jump of wavelength in semiconductorlaser. This focus offset interferes with the focus offset occurring nearthe header region, thereby the focus control is made to be furtherunstable, causing a failure in recording.

[0122] So, in this embodiment, the unstable-focus-control condition canbe avoided by using servo error signal from the sample hold circuit 41that uses the output of header region signal from the header regiondetector 30, holding a focus error signal value of at least severalbytes of sector format before the output time, from the finish of headerregion signal until just before the recording starts.

[0123] However, even in this composition, when the transfer functionvaries due to a deterioration of actuator system with age, the focuscontrol may be unstable. So, in this embodiment, further by measuringsignal of focus offset waveform occurring at the header region to bedetected by the header region detector 30 by a previous learning etc.,then subtracting this from the servo error signal in the adder circuit44, the focus follow-up performance can be stabilized. Also, other thanthe simple reverse function of focus offset waveform, an arbitrarywaveform generated by the arbitrary waveform generating circuit 40 canbe added or subtracted to produce servo error signal while securing thestability of the servo control system including actuator system.

[0124] The arbitrary waveform may be, for example, a rectangular pulsewith arbitrary height and width. Here, the arbitrary values may bedetermined taking a step response waveform of the servo system includingactuator system into account. Also, they may be, of course, a DC valuesimply. This corresponds to the simple adding/subtracting of focusoffset, and, in this case, by using write gate signal (WGATE) which isgate signal for the start of recording, the timing of adding/subtractingmay be controlled. Thus, the focus offset can be switched between theplayback and the recording. Also, the selection of signal from thearbitrary waveform generating circuit 40 can be conducted based onland/groove signal from the system controller or the track regiondetector, described earlier, that conducts the detection of land/groovesignal to detect whether the recording track scanned by light beam is aland region or a groove region.

[0125] Meanwhile, though not shown, the arbitrary waveform generatingcircuit 40 is, for example, composed so that an A/D converter takes infocus error signal, e.g., only near the header region for apredetermined time, accumulating it into a RAM memory, and a D/Aconverter converts it when outputting the signal. By this composition,the reverse function of focus offset waveform can be obtained. Also,when generating a true arbitrary waveform, by providing an operationmeans to develop the function on a RAM memory, the signal can be outputby using a D/A converter.

[0126]FIG. 14 is a block diagram showing the main part of an opticaldisk device in the sixth preferred embodiment according to theinvention.

[0127] The optical disk device in this embodiment, which is applied toan optical disk as shown in FIGS. 3 and 5, comprises a playback addsignal circuit 109 to output track add signal of the division typeoptical detector 108, an envelope detection circuit 50 to output theenvelop signal of track add signal, a binarization circuit 51 tobinarize the envelope signal, a burst detection circuit 53 to outputburst detection signal from burst signal with a specific mark includingthe track add signal, and a logical operation circuit 52 to outputheader region signal, which is binarized signal almost enclosing theheader region, from output signal of the binarization circuit 51 and theburst detection signal. Here, the burst signal with a specific mark issignal VFO1 of pre-pit region shown in FIG. 4, and is single-cyclesignal, such as a 3T mark.

[0128]FIG. 15 is a waveform diagram showing the operation of the opticaldisk device in this embodiment.

[0129]610 is track add signal, 611 is signal near the header region, 612is a recording data region, and 613 is an erase level (unrecorded level)in a phase change disk. When output level of envelop signal to the trackadd signal 610 is 615 and the threshold level of the binarizationcircuit 51 is set to be at the middle level between 615 and 613, roughheader detection signal 616 is output. In this simple composition, therough header detection signal 616 must be output even for a defect ordust in optical disk.

[0130] To solve this problem, burst detection signal 617 in VFO1 regionis detected by the burst detection circuit 53, the rough headerdetection signal 616 is subject to a logical operation by the logicaloperation circuit 52 composed of, e.g., a flip-flop circuit, therebyheader region detection signal with a good reliability can be output.

[0131] Then, the logical operation circuit 52 counts by an interval,e.g., between the header region and the following sector's header regionby a byte counter circuit, thus header region signal 619, which isbinarized signal almost enclosing the header region, is output.

[0132] Although in this embodiment the burst signal is detected from thetrack add signal, it may be detected from push-pull signal, which istrack difference signal.

[0133]FIG. 16 is a block diagram showing the main part of an opticaldisk device in the seventh preferred embodiment according to theinvention.

[0134] In an optical disk as shown in FIGS. 3 and 5, when there existsclearly a crosstalk component from the neighboring header at theposition where sector address information is played back as shown inFIG. 4, crosstalk replica signal is easy to generate.

[0135] Thus, the optical disk device in this embodiment comprises acrosstalk replica signal generating circuit 60, a subtraction circuit 61to subtract the crosstalk replica signal from the pre-pit signalcomponent of track add signal, e.g. by using timing control signal fromthe system controller (not shown), and an address playback circuit 24 toplay back address information from output of the subtraction circuit 61.Meanwhile, in using no timing control signal, the crosstalk replicasignal may be subtracted uniformly from the pre-pit signal componentonly when the header region detection signal is output.

[0136] When focused beam scans a land region, the crosstalk replicasignal generating circuit 60 generates a replica of pre-pit playbacksignal with 3T mark so as to remove a crosstalk component from VFO2 inthe neighboring pre-pit region, generating crosstalk replica signal bysetting the gain ratio to the pre-pit signal component to be, e.g. 15%,taking the crosstalk amount into account.

[0137] On the other hand, when focused beam scans a groove region, itmay be composed so that a crosstalk component from VFO1 of theneighboring pre-pit region can be removed. For example, the crosstalkreplica signal generating circuit 60 is, like the composition of thearbitrary waveform generating circuit described earlier, composed of anoperation means to develop the function on a RAM memory, where thesignal is output by using a D/A converter.

[0138] Although in this embodiment the sector address information etc.is played back from the track add signal, the sector address informationmay be played back from push-pull signal, which is track differencesignal.

[0139] Meanwhile, in the optical disk of this invention, the neighboringpre-pit regions in the header region with may have different lengths sothat parts of address information in the neighboring pre-pit regions arenot aligned in the radius direction.

[0140] Although a phase change type optical disk are used in the aboveembodiments, a magneto-optic disk and a playback only reflection typeoptical disk are also applicable. Also, the optical disk devices in theabove embodiments are applicable to the playback/recording of theseoptical disks.

[0141] Although the (1,7) modulation system and the mark edge recordingare used in the embodiments, coding of other modulation/demodulationsystem and a mark position recording may be used.

[0142] Although the ZCLV system for the rotation control of optical diskis used in the embodiments, a ZCAV (zoned constant angular velocity)system or a simple CAV system may be used.

[0143] Further, although in the embodiments the sector addressinformation etc. is played back from the track add signal, the sectoraddress information may be played back from push-pull signal, which istrack difference signal.

[0144] Although in the embodiments the compositions to solve the problemof the optical disk described in Japanese patent No. 2,663,817 aredisclosed, another header arrangement can be used so that parts ofaddress information in the pre-pit regions neighboring in the radiusdirection are not aligned in the radius direction. For example, alsoapplicable is a composition, which is described in Japanese patent No.2,788,022, that pre-pits are arranged on the right and left sides of theboundary of land and groove.

[0145] Advantages of the Invention:

[0146] In the optical disk of the invention, the pre-pit regionsincluding specific information are formed at the boundary part ofneighboring land region and groove region and are disposed every otherboundary part, and specific information's in the neighboring pre-pitregions are not aligned in the radius direction of the optical disk.Therefore, the crosstalk effect from the neighboring pre-pit region canbe suppressed. Even when defocusing of light beam occurs due to an errorin the manufacturing of head or a deterioration in head performance withage, misidentification of address information in the pre-pit region canbe reduced significantly. Accordingly, the reduction of throughput inthe optical disk device can be prevented, thereby the reliability ofdevice or disk can be enhanced.

[0147] On the other hand, in the conventional optical disk device, therewere problems as follows: the influence of the pre-pit to servo errorsignal is to cause the focus offset and the disorder of track errorsignal, thereby incurring a unstable recording/playback. Further, whenstarting the recording after passing the header region, depending on thecomposition of optical head, there occurs a focus offset due to thechromatic aberration of objective lens, by a phenomenon called a jump ofwavelength in semiconductor laser, thereby causing a failure inrecording.

[0148] In contrast with this, the optical disk device of this inventioncan offer stable header detection and address identification. Also, thesharing of address by land and groove can be performed with a goodreliability. Further, the stability of playback/recording at data regioncan be enhanced.

[0149] Although the invention has been described with respect tospecific embodiment for complete and clear disclosure, the appendedclaims are not to be thus limited but are to be construed as embodyingall modification and alternative constructions that may be occurred toone skilled in the art which fairly fall within the basic teaching hereis set forth.

What is claimed is:
 1. An optical disk device for conducting therecording/playback of an optical disk comprising a land region and agroove region that are formed on a substrate, said land region andgroove region being used as a recording track that is the medium of therecording/playback of information signal, and a pre-pit region includingaddress information, comprising: means for outputting signal to detectwhether a recording track scanned by light beam is a land region or agroove region; a header region detection means for detecting a headerregion including the pre-pit region; and a servo error detection meansfor sampling a track error signal value at an arbitrary time before theoutput time of said header region detection means, and holding saidtrack error signal value an arbitrary time or conducting an operation ofsaid track error signal value and arbitrary waveform signal thenoutputting the operation result as servo error signal.
 2. An opticaldisk device for conducting the recording/playback of an optical diskcomprising a land region and a groove region that are formed on asubstrate, said land region and groove region being used as a recordingtrack that is the medium of the recording/playback of informationsignal, and a pre-pit region including address information, comprising:means for outputting signal to detect whether a recording track scannedby light beam is a land region or a groove region; a header regiondetection means for detecting a header region including the pre-pitregion; and a servo error detection means for sampling a focus errorsignal value at an arbitrary time before the output time of said headerregion detection means, and holding said track error signal value anarbitrary time or conducting an operation of said focus error signalvalue and arbitrary waveform signal then outputting the operation resultas servo error signal.